Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!bu.edu!m2c!applix!jimr
From: jimr@applix.com (Jim Rouleau [ext 256])
Newsgroups: comp.compression
Subject: LZW Patent rights (was looking for info on image compression)
Message-ID: <1173@applix.com>
Date: 27 Mar 91 16:56:06 GMT
Organization: APPLiX Inc., Westboro, MA
Lines: 24

>jones@pyrite.cs.uiowa.edu writes:
>
(PS:  Does the use of Ziv-Lempel compression for GIF images mean that
>>the question of patent rights for the Ziv-Lempel algorithm applies to
>>GIF images?


news@ai.mit.edu responds:
>
>It definitely does, assuming GIF format uses LZ compression and the
>patent is considered valid.  Only a lawsuit will determine actual
>coverage.  If the algorithm differs somewhat from LZ you may be safe
>(but consult a lawyer).

  Now I'm confused.  According to the TIFF 5.0 spec (prepared jointly
by Microsoft and Aldus) compression scheme 5 is "LZW Compression".
In fact, "A Technique for High Performance Data Compression" by
Terry A. Welch is cited as the reference, which is then fully
described in the spec.

  Are Microsoft and Aldus at risk for doing this ???  (maybe my
TIFF reader should not support scheme 5 !!)

       jimr